The flowsheet shown is of a conventional type, for treatment of 200-300 tons per day of fluorspar ore containing lead, using “Sub-A” Flotation.
If lead and zinc were present, the same flowsheet would apply to remove a bulk sulphide concentrate which could be subsequently refloated to produce the respective lead and zinc concentrates suitable for marketing.
The best approach to effectively produce separate lead and zinc concentrates should be established by test work. In some cases, selective flotation is indicated initially. This may be accomplished by removing a lead concentrate, then following this process by conditioning and flotation of the lead tailing to produce a zinc concentrate.
Crushing Circuit
Primary and secondary crushing are used for this plant tonnage. Single stage crushing may be employed for tonnages up to 100 tons per day.
Grinding Circuit
Two stage grinding, using the Rod Mill in open circuit, followed by closed circuit ball mill grinding, is ideal because of the local power requirement and the increased efficiency of grinding.
The Selective Mineral Jig may be utilized to recover galena in this circuit. Presence of oxidized lead in the ore is overcome to a great extent by removing it at a relatively coarse size, in the jig.
Conditioning Tank
Conditioning of the classifier overflow is required if sulphidization is employed to effect flotation of oxidized lead. A second stage conditioning of the thickened lead tailing, after repulping with fresh water, is required for flotation of the fluorspar. Heating of the pulp at this point is often advantageous.
Fluorspar Flotation
The lead and fluorspar are recovered by Flotation of the cell-to-cell type, permitting maximum recovery and grade of concentrate. Wide acceptance of machines is well verified when considering that over 95% of all acid grade fluorspar is processed in the “Sub-A” Flotation Machine. Flexibility of these machines is of prime importance where such high specifications must be met. Multiple cleaning, always necessary in acid grade fluorspar plants, can be performed without the help of pumps.
Lead tailing is thickened to remove the bulk of the reagents used in the lead circuit. The clear overflow is re-circulated to the grinding circuit.
Thickening and Filtering
Both concentrates are thickened and filtered. The thickened lead concentrate is filtered on the Disc Filter. Thickened fluorspar concentrate, at approximately 60% solids here, has a high filter capacity of approximately 2000 pounds per sq. ft. per 24 hours. The Fluorspar Filter with its stainless steel filter media, is especially designed for this application.
Drying and Storage
The Standard Dryer effectively dries the filtered fluorspar concentrate to less than 0.5% moisture, as required for marketing. An elevated temperature in the dryer can also be used to burn off small amounts of sulphur and lead.
A screw conveyor and bucket elevator as employed to transport the dried fluorspar to the concentrate storage bins. Bins can be conveniently discharged into rail road cars for shipment, while the filtered lead concentrate may be marketed as produced, without drying.
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Acid Grade Fluorspar Beneficiation Process Machinery And Production Line Images
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